Salas DCG3 preamp (line & headphone)

[transcendent]

DCG3 with UltraBiB. R1 2.4R (neg) 2.0R (pos) 5W would work?

 

[Salas]

What bias used on DCG3?

 

[PKI]

Salas what would be the best way to make an additional output to connect a powered subwoofer to the preamp?

 

[Salas]

Either a buffer op-amp or at least 100 Ohm resistors from the main output RCAs to the subwoofer output ones. Center pin to center pin.

 

[PKI]

Thank you!

 

[transcendent]

What bias used on DCG3?

Looking for ~110mA.

 

[Salas]

One UBiB per polarity (shared PSU between channels) should have 1.8R R1 in the NEG and 1.1R in the POS

 

[transcendent]

One UBiB per polarity (shared PSU between channels) should have 1.8R R1 in the NEG and 1.1R in the POS

It's dual mono configuration, forgot to mention..

 

[PKI]

Stupid question... as usual hehe . Why different resistors for + and -?

 

[Salas]

It's dual mono configuration, forgot to mention..

Then use 2.4R in each NEG and 1.8R in each POS

 

[Salas]

Stupid question... as usual hehe . Why different resistors for + and -?

+Rail swings current -Rail is just CCS in this preamp circuit

 

[transcendent]

Then use 2.4R in each NEG and 1.8R in each POS

Thanks Salas! 5W square whitish OK?

 

[Salas]

2W is more than enough and there is metal film low ppm also to find in this power rating

 

[transcendent]

Already picked up everything from mouser, wouldn't want to do another order.. so have to choose from what's in local stores. 2.4R non-existent, especially in metal film. Will have to go for these 5W as it is the only option

 

[Salas]

Not the end of the world. White cement brick resistors should work well enough and there is space provision for big parts in the UBiB's R1 place

 

[PKI]

+Rail swings current -Rail is just CCS in this preamp circuit

I see, thank you! From UBIB manual I understood that the resistors are limiters, so why just not put two 1R8?

 

[Salas]

To save some total dissipation in the box

 

[PKI]

I see, make total sense.

 

[IDM]

Hi,

After all the issues with a fried J1. I finally got the DCG3 finished and whilst not completely boxed up yet, I have been able to drop it into the system. I am using to feed my Pass F5 and I have to say it is truly superb. It just seems so agile, detailed but musical. I am totally delighted.

So again thanks for the advise in getting it sorted.

I am using it with dual mono PSU with 4X ultraBIB regs and I see a few posts back that I should change the R1 values for the negative and positive regs.

 

[Salas]

Congratulations!

Using BC327 for Q1 Q2 already I suppose. What R1s you use in the UBiBs, and is the dissipation manageable?